Generally

§415.1 Short title.

§415.2 Definitions.

For the purposes of this part, except as otherwise required by the context:

Project means the same word as defined by section 1.2(g) of the Delaware River Basin Compact.

Floodway means the channel of the watercourse and those portions of the adjoining flood plains which are reasonably required to carry and discharge the regulatory flood. For this purpose the limit of the floodway shall be established by allowing not more than a one-foot rise of the water surface elevation of the regulatory flood as a result of encroachment. Wherever practical, equal conveyance reduction from each side of the flood plain shall be used. (See Figure 1.)

Flood fringe means that portion of the flood hazard area outside the floodway.

Flood hazard area means the area inundated by the regulatory flood.

Flood plain means the area adjoining the channel of a stream which has been or hereafter may be covered by flood water.

Floodproofing means any combination of structural and nonstructural additions, changes, or adjustments to properties and structures which reduce or eliminate flood damage to lands, water and sanitary facilities, structures, and contents of buildings.

Flood protection elevation means one foot above the elevation of the flood that has a one percent chance of occurring in any one year. (The 100-year flood).

Pennsylvania

Delaware

Brandywine Creek, Christina.

New York

East Branch, Mongaup, Neversink, West Branch.

New Jersey

Assunpink, Musconetcong, Paulins Kill, Rancocas, Pequest.

Official flood plain map means a map showing the flood plain area of a community prepared pursuant to the National Flood Insurance Act, or a map recognized by the Executive Director as meeting equivalent hydraulic or engineering criteria.

Regulatory flood means the flood which has a one percent chance of occurring in any one year. (The 100-year flood.)

Structure means any assembly of material above or below the surface of land or water, including but not limited to, buildings, dams, fills, levees, bulkheads, dikes, jetties, embankments, causeways, culverts, roads, railroads and bridges.

(8) Land and water use regulations of responsible units of government shall not impair or conflict with the flood plain use standards duly adopted for the basin, except as provided for in §415.42(a) of this part.

(9) Plans for land and water use adopted by responsible agencies shall not impair or conflict with these flood plain use standards.

(10) No action of any unit of government shall impair or conflict with these flood plain use standards.

Types of Projects and Jurisdiction

§415.20 Class I projects.

Projects described in paragraphs (a) and (b) of this section shall be subject to review by the Commission under standards provided by this section and in accordance with the provisions of §§415.30 through 415.33 of this part, as follows:

(a) All projects subject to review by the Commission under section 3.8 of the Compact and the regulations thereunder.

§415.21 Class II projects.

Class II projects, subject to review in accordance with §§415.40 through 415.43 of this part, include all projects other than Class I projects, in non-tidal areas of the basin, which involve either:

(a) A development of land, either residential or non-residential within a flood hazard area which:

(1) Includes one or more structures covering a total land area in excess of 50,000 square feet; or

(2) Contains in excess of 25 residential building lots or 25 dwelling units as part of an integrated development plan whether or not such development is included in a single application; or

(b) A development of land in the flood hazard area to mine, manufacture, process, store or dispose of materials which, if flooded, would pollute the waters of the basin or threaten damage to off-site areas, including, without limitation thereto, materials which are poisonous, radioactive, biologically undesirable or floatable.

§415.32 Permitted uses generally.

(a) Within the floodway, the following uses are permitted to the extent that they do not require structures, fill or storage of materials or permanently installed equipment, and do not adversely affect the capacity of the floodway:

(2) Residences and other structures constructed so that the first floor, including basement, is above the Flood Protection Elevation. When fill is used the finished fill elevation shall be no lower than the Flood Protection Elevation for the particular area and shall extend at least 15 feet beyond the limits of any structure or building erected thereon.

(b) Within the flood fringe the following uses by special permit may be authorized under standards hereinafter provided:

(1) Non-residential uses generally. Structures other than residence shall ordinarily be elevated as herein provided but may in special circumstances be otherwise flood proofed to a point above the Flood Protection Elevation.

(2) Commercial uses. Commercial structures shall be elevated so that no first floor or basement floor is below the Flood Protection Elevation; or such structures may be flood proofed to the Flood Protection Elevation. Accessory land uses, such as yards, railroad tracks and parking lots may be at lower elevations. However, a permit for such facilities to be used by the general public shall not be granted in the absence of a flood warning system, if the area is inundated to a depth greater than two feet or subject to flood velocities greater than four feet per second upon the occurrence of the Regulatory Flood.

(3) Manufacturing and industrial uses. Manufacturing and industrial buildings, structures, and appurtenant works shall be elevated so that no first floor or basement floor is below the Flood Protection Elevation; or such structures may be flood proofed to the Flood Protection Elevation. Measures shall be taken to minimize flood water interference with normal plant operations especially for streams having protracted flood durations. Certain accessory land uses as yards and parking lots may have lesser protection subject to the flood warning requirements set out in 2 above.

(4) Utilities, railroad tracks, streets and bridges. Public utility facilities, roads, railroad tracks and bridges shall be designed to minimize increases in flood elevations and shall be compatible with local comprehensive flood plain development plans to the extent applicable. Protection to the Flood Protection Elevation shall be provided where failure or interruption of these public facilities would result in danger to the public health or safety, or where such facilities are essential to the orderly functioning of the area. Where failure or interruption of service would not endanger life or health, a lesser degree of protection may be provided for minor or auxiliary roads, railroads or utilities.

(5) Water supply and waste treatment. No new construction, addition or modification of a water supply or waste treatment facility shall be permitted unless the lowest operating floor of such facility is above the Flood Protection Elevation, or the facility is flood proofed according to plans approved by the Commission, nor unless emergency plans and procedures for action to be taken in the event of flooding are prepared. Plans shall be filed with the Delaware River Basin Commission and the concerned state or states. The emergency plans and procedures shall provide for measures to prevent introduction of any pollutant or toxic material into the flood water or the introduction of flood waters into potable supplies.

Administration

§415.40 Administrative agency.

(a) Class I projects as defined by §415.20 of this part shall be subject to review and approval by the Commission.

(b) Class II projects as defined by §415.21 shall be subject to review and approval by a duly empowered state or local agency; and if there be no such state or local agency at any time on and after January 1, 1978, and only during such time, the Commission may review any such project which has been identified by the Executive Director as having special flood hazards, and:

(1) Is located along the mainstem Delaware River or a major tributary thereof, or

§415.41 Special permits.

A special permit may be granted, or granted on stated conditions, provided:

(a) There is a clear balance in favor of the public interest in terms of the following environmental criteria:

(1) The importance of a facility to the community.

(2) The availability of alternative locations not subject to flooding for the proposed use.

(3) The compatibility of the proposed use with existing development and development anticipated in the foreseeable future.

(4) The relationship of the proposed use to any applicable comprehensive plan or flood plain management program for the area.

(5) The safety of access to the property in times of flood for ordinary and emergency vehicles.

(6) The expected heights, velocity, duration, rate of rise and sediment transport of the flood water expected at the site.

(7) The degree to which the proposed activity would alter natural water flow or water temperature.

(8) The degree to which archaeological or historic sites and structures, endangered or rare species of animals or plants, high quality wildlife habitats, scarce vegetation types, and other irreplaceable land types would be degraded or destroyed.

(9) The degree to which the natural, scenic and aesthetic values at the proposed activity site could be retained.

§415.42 Technical standards.

(a) Standards used by state and local governments shall conform in principle to Commission standards but may vary in detail provided that resulting flood plain use will not be less restrictive than would result from the application of Commission standards. The Commission will review proposed state and local flood plain regulations to determine their compliance with Commission standards.

(b) Because of the variety and diversity of presently recognized hydrologic procedures, no one procedure or method is prescribed for determining the peak flow in cubic feet per second for the 100-year storm (Q 100) on which profiles for the delineation of flood hazard areas are based. The following may be used:

State and local agencies may use methods resulting in Q 100s which are in reasonable agreement with those of the Commission. Any significant difference shall be reviewed with and subject to approval by the Executive Director.

(c) Methods and procedures shall be uniform, so far as practicable, within sub-basins which have a major effect on the larger basins of which they are a part. To assist in achieving this objective the Commission staff will periodically provide to the various interested governmental agencies and others Q 100 data as developed by the Delaware River Basin Commission Hydrology Coordinating Committee for key locations in the Delaware River Basin. These will be based on a Log Pearson Type 3 analysis of data from the U.S.G.S. gaging stations using station skew, regional skew, or weighted skew, depending on the scope of data at each station.

§415.43 Mapped and unmapped delineations.

(a) Whenever an official flood plain map providing the pertinent information is available with respect to a given project, the map shall be used for the delineation of the flood hazard area, floodway, flood fringe and determination of flood protection elevation.

(b) Whenever an official flood plain map providing the required information is not available with respect to a given project, the administrative agency shall require the project landowner to submit details concerning the proposed uses as needed to determine the floodway and flood fringe limits at the proposed site, including: cross-sections of the stream channel and overbanks, stream profile, and factors involved in determining obstructions to flow. From the data submitted, soil surveys, historic flood maps, high water marks and other empirical data, the applicant, subject to verification by the administrative agency, shall calculate flood hazard areas, and establish the flood protection elevation for the particular site.

(c) Pending the preparation and completion of flood plain mapping, a “general flood plain” area shall be prescribed by the administrative agency to delineate for public guidance the areal limits of site locations which are required to be submitted for review under this regulation.

Enforcement

§415.50 General conditions.

On and after January 1, 1978, where:

(a) The flood hazard at the site is clear, present and significant, or the local government having jurisdiction has special flood hazard areas identified pursuant to the National Flood Insurance Act; and

(b) The site is not subject to an approved state or municipal regulatory system having the same or similar effect on the flood hazard as this regulation, the Commission may condition its approval on any local governmental project under section 3.8 of the Compact upon the adoption and enforcement of flood plain regulations, approved hereunder, by the state or local government having jurisdiction.

§415.51 Prior non-conforming structures.

A structure which was lawful before the adoption of this regulation but which is not in conformity with the provisions hereof, shall be subject to the following conditions (to be enforced by the appropriate authority as to Class I and Class II projects, respectively, under §§415.40 through 415.43 of this part):

(a) A non-conforming structure in the floodway may not be expanded, except that it may be modified, altered or repaired to incorporate flood proofing measures provided such measures do not raise the level of the 100-year flood.

(b) A non-conforming structure in the floodway which is destroyed or damaged by any means, including a flood, to the extent of 50 percent or more of its market value at that time may not be restored, repaired, reconstructed or improved except in conformity with the provisions of these regulations.